1. Field of the Invention
The field of the invention relates to telecommunications, an in particular, to mitigating the consequences to a service network of the failure of an access network.
2. Description of the Prior Art
Recently, service providers have begun to partner with cable multi-system operators (MSO) to provide customer access for services. Examples of services include video on demand and voice over Internet protocol (VoIP) service, as well as other services. Other times, a service provider provides its own access. In either case, access is typically considered a general service over which other services, such as VoIP, are provided.
Occasionally, customers lose access in the event of an access failure. For instance, equipment in the access network could fail. Other causes of access loss are possible. In the even of an access failure, most customer equipment monitors for access restoration and then initiates a restoration process. Unfortunately, if the access failure is a mass event, then a large number of customers will initiate their restoration processes simultaneously. Such a mass restoration event could possibly overload elements in the service network.
FIG. 1 illustrates a communication network in an example of the prior art. Communication network 100 includes service network 110 coupled to access networks 120, 130, 150 and 150 by session border controllers (SBC) 112, 113, 114, and 115 respectively. Session border controllers are well known network elements that manage traffic flow across network borders. Access network 120 includes devices 121, 123, and 122. Access network 130 includes devices 131, 133, and 132. Access network 140 includes devices 141, 143, and 142. Lastly, access network 150 includes devices 151, 153, and 152.
FIG. 2 illustrates an operational situation in the prior art. To begin, device 121 has a session connection over access network 120 to SBC 112, and in turn, to service network 110. Likewise, device 122 has a session established with service network 110 via SBC 112 and access network 120. Device 123 has also established a session with service network 110 over SBC 112 and access network 120.
As illustrated, an access cessation event causes the loss of the service sessions established by devices 121, 122, and 123. Namely, due to the loss of access, devices 121, 122, and 123 are no longer able to continue their sessions.
Eventually, access is restored and an access restoration signal is applied to devices 121, 122, and 123. In response to detecting the access restoration signal, devices 121, 122, and 123 all simultaneously initiate service restore requests to SBC 112. The service restore requests, on a larger scale, could crash SBC 112.